81849217 has 4 divisors (see below), whose sum is σ = 84061396. Its totient is φ = 79637040.

The previous prime is 81849211. The next prime is 81849227. The reversal of 81849217 is 71294818.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 58384881 + 23464336 = 7641^2 + 4844^2 .

It is a cyclic number.

It is not a de Polignac number, because 81849217 - 2¹¹ = 81847169 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81849217.

It is not an unprimeable number, because it can be changed into a prime (81849211) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1106034 + ... + 1106107.

It is an arithmetic number, because the mean of its divisors is an integer number (21015349).

Almost surely, 2^81849217 is an apocalyptic number.

It is an amenable number.

81849217 is a deficient number, since it is larger than the sum of its proper divisors (2212179).

81849217 is a wasteful number, since it uses less digits than its factorization.

81849217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2212178.

The product of its digits is 32256, while the sum is 40.

The square root of 81849217 is about 9047.0557089033. The cubic root of 81849217 is about 434.1816949659.

The spelling of 81849217 in words is "eighty-one million, eight hundred forty-nine thousand, two hundred seventeen".